All Sky Camera

w7ay

mikeinlehigh Like this?

The focal length of that one is way too long, Mike.

The one I use has a focal length of 3.2mm and even that is not short enough if you want horizon-to-horizon coverage with an IMX178 sized sensor. (And does not have sufficient image circle to cover larger sensors.)

C mount lenses often have two specifications: one is the resolving power (often stated in megapixels) and the other one is the image circle (for example, 1/1.7" format, in the case of the sensor I used; sensor format refers to the equivalent diameter of a vidicon tube that were used in old television cameras).

Make sure (1) the image circle is large enough for the diagonal of the sensor, and (2) the resolving power is enough to match the pixel size of the sensor.

Chen

Stars2962

Anyone have a link for a currently available fisheye that is appropriate for the ASI224MC since the one everyone recommended a year or so ago is no longer available?

mikeinlehigh

I think i'll order the lens you have Chen. The price is certainly right. I currently have a ASI385MC that I bought on sale and was going to use for planetary imaging. Deep Sky stuff always seems to take precedence so it hasn't been used yet. It does have a much small sensor than your ASI178, which is onsale right now. ASI178 - 6.4mb 3096 x 2080 to ASI385 - 2.1mb 1936 x 1096. Nice job on the enclosure Chen. Well engineered 🙂

Edit: When the stock ZWO lens is removed the adapter comes with it. Is that able to be separated from the lens? Obviously the threads on the camera are too wide to accomadate a C thread. If so, that adapter is really on the stock lens. Going to take some force to separate it.

w7ay

mikeinlehigh Is that able to be separated from the lens? Obviously the threads on the camera are too wide to accomadate a C thread. If so, that adapter is really on the stock lens. Going to take some force to separate it.

If your camera originally came with a ZWO lens, you already have a Cs-to-T2 adapter sitting around. Otherwise, there are also plenty of them around (even ScopeStuff) and ZWO even sells one:

https://astronomy-imaging-camera.com/product/m42-to-cs-adapter

If memory serves, that Amazon lens is a Cs lens (sometimes written CS), and not a C lens. Same thread size, but the flange focal distance is 5mm shorter (12.5 mm instead of 17.5 mm for C). I don't remember if the ZWO lens was a C or Cs, so you may need to do some literature digging, or simply experiment.

The barrel shaped ZWO camera do come with a 5mm C mount spacer, I think -- so if you have one of those, you already have a 5mm spacer, in case you need one. Otherwise, lots of places have them, ditto ScopeStuff. I am sure you can find them at Amazon or EBay too.

Be mindful that with your smaller sensor, you would have an even smaller FOV that I have with an ASI178. It is not directly proportional (because of FishEye geometry) but you can use the sensor size difference as a rough guess of what your FOV would be with that same lens. I think you might be better off looking for something like a 1.6mm to 2mm Fisheye.

Have fun.

Chen

w7ay

mikeinlehigh ASI178, which is onsale right now. ASI178 - 6.4mb 3096 x 2080

By the way, MIke, the only reason ithe ASI178MC is on sale is that it has been superceeded by the ASI678MC (uses Sony IMX678 sensor). The lower price is just to clear the existing inventory.

The IMX678 sensor has the same pixel count as the IMX178, but the pixel size is smaller (2 µm vs 2.4 µm), and the read noise is substantially lower, and has more near-IR sensitivity (IR sensitivity probably not a big deal for an all sky camera). Because of the smaller pixel, the sensor itself is also smaller (thus requires even shorter focal length length when all else is equal).

You might want to factor this (obsolete camera) in your decisions. You might not want to throw good money on something that now has very low resale value, if that is part of your purchasing equation.

I myself found that the IMX178 already has insufficiently large sensor. So, a ASI678 will be a worse match for my needs, although I have one on order with my dealer (but for use in a guide scope).

An ASI178MC at gain of 270 (max setting in ASIAIR unfortunately; INDIGO should do better) already requires a 10 second exposure to register the Milky Way. At that point, the stars are already trailing (yes, even on a fisheye FOV :-). That is why I am going to a DSLR lens (larger aperture for the same f/number to catch more photons) and compensate for the longer focal length with an even larger sensor -- a spare ASI294MC for now).

Just do everything on paper first before buying anything.

Chen

w7ay

mikeinlehigh

Oh, I forgot to mention, get yourself a bottle of Rain-X rain repellant glass cleaner (the one that you use on windwhield of cars). I have not seen it mentioned for an All SKy camera, but I have found that It is a bit better than Windex, which in turn is better than water.

Chen

mikeinlehigh

Thanks for the great input Chen. I bought the ASI385 on sale only to find it's been replaced but that was several months ago. Oh well, I'll find a use for it. So I agree on the 178. I'd rather spring for the newer camera. So, smaller pixel size is going to be better on an All sky camera? I guess the "formula" for pixel size along with focal length applies here? Also, great idea for using Rain X. Most of my time is spent on deep sky stuff using the ASI294MC Pro. I used to be really into planetary photography a few years ago using a C14. However the lengthy cool down times and the constantly changing sky conditions, by the hour, in here Southwest Florida made me give up. Although deep sky does depend on sky conditions it's not nearly as risky. So, I just planetary image on occasion now with a Meade 8" LX200 ACF . So, I'm thinking about the newer ASI585MC for that. Oh I've gotten way off topic now. My apologies to the moderators 😁.

w7ay

mikeinlehigh Oh I've gotten way off topic now.

Heh, you started this thread; it is not as if you have hijacked someone else's thread :-).

Keep in mind that although a smaller pixel is better matched as far as plate scale, for the same number of total pixels (like the IMX178 vs IMX678 case), the sensor dimension will be smaller, and you need to compensate with a shorter focal length lens if you want the same FOV. Secondly, the sensitivity will also drop, but in the case of the IMX678 vs IMX178, it is actually better because the read noise is lower -- but that is not always the case. And with such a short focal length, plate scale is on your side.

Have fun, Mike.

It is surprising how many people are building all sky cameras. With that many people, you would think someone would be enterprising enough to market an affordable and attractive turn-key package by now.

Chen

mikeinlehigh

As a serious astrophotographer I accept the fact that I've spent several thousand dollars on equipment. It's a lifelong passion. Good equipment is expensive. Fine optics are expensive. They always have been. An allsky camera is a luxury. Sure many have plunked down a grand for theirs. I might spend a lot but I do it wisely. A thousand dollars for one? I just can't justify it especially if one can be built in a few hours for a third of the price 😁. Thanks again for your help and insight.

w7ay

mikeinlehigh A thousand dollars for one? I just can't justify it especially if one can be built in a few hours for a third of the price

Me neither. I can afford it, but don't want to support people who gouge.

By the way, I just pointed one of my Amazon Blink cameras straight up (yep, 100% overcast -- i.e., normal, in Portland). Located close to my All Sky camera whose images I posed earlier. "Borrowed" from the Blink that I use to point to our garden, thus the name :-).

Looks almost as wide length wise, but not as tall in height as my all sky camera (which is not horizon-to-horizon).

I'll see if it can pick up any stars at night (it might be "clear" tonight but with terrible transparancy). Will report back.

I am sure it will go into "monochrome" mode at night (same kind of near IR sensitivity of the IMX678, where the R, G and B sensitivities all bunch together to form a monochrome image at the 850 nm region.

So, no star colors for sure (not that the IMX178 could pick up that much star colors anyway :-).

But if it is actualy sensitive enough to see stars (it picks up deer at night :-), we can add some optics to it to get a wider angle (perhaps even the cheap "wide angle" attachments for smartphones).

If the darn thing is sensitive enough, it can be the "turnkey" all sky camera for the masses (especially the masses that already have the Blink system at home, since it does need a Blink hub in addition to the camera module. At least it can warn you of clouds directly overhead (rain!), even with its existing camera angle. At least the wireless range is fantastic to the hub, and the hub just has to see the home WiFi system. I also have the third party solar panels to go with each of my Blinks, although I doubt it will last more than a few dozen pictures, so this will need a microUSB cable to feed 5V to it.

Chen

mikeinlehigh

I'll probably go a lot more simple Chen. Camera in a good enclosure of course but a 30' long powered usb cable coming inside to a spare laptop running "AllSkyEyePro" software by Michael Poelzl. I have weather instruments so hole already drilled through the concrete block for cables. Camera enclosure can be mounted right outside on the roof. I've already tested the whole setup on a tripod and it performed perfectly. Software is easy to use and highly programmable. Honestly, this is more of a novelty for me. Can check at a glance to sky conditions before going out to open the observatory roof. I can control my whole imaging setup from my office, once the roof is open and scopes uncapped. I like to periodically check my imaging progress once it's up and running. The allsky cam will let me check the sky conditions at the same time. I often set up another scope on my patio to observe while the imaging scope in the obsy is running. But if it's late night and I'm tired it's nice to have an eye to the sky from inside the house 😁. So you can see why I'm budget minded on this project. I do enjoy taking the video from last night and converting it to a time lapse. Fun to look for meteors etc.

w7ay

mikeinlehigh

Mike, the Blink does not work out anyway.

When it got dark, the Blink went into low resolution Mono binning, and even so has very low sensitvity compared to the ASI178MC with the 3.2mm/1.7 lens. I could currently (just left civil twilight for nautical twilight) see Vega easily with a 1sec exposure, Bin 1 and gain of 92 on the ASI178MC, while nothing appears on the Blink's mono-binned auto exposure frame.

Fun to look for meteors etc.

I have yet to see one meteor on my all sky camera (even tried a sequence of 1 minute back to back exposures just last year on August 13th). But have multiple occasions seen sporadic meteors (and one case, possibly a bright Perseid crossing Cygnus a couple of years ago) when I doing long exposures. I think a large camera lens will be better as a meteor camera (perhaps even the Samyang I will be using with my next generation all sky camera). Perhaps a couple of them, pointing to different parts of the sky.

I still remember in my youth lusting for an Aero-Ektar with a 4x5" plate holder, but could not afford to build a meteor camera like that. Those lenses are really rare nowadays (radioactive lens coating? I believe). But nowadays, a 50mm/1.4 camera lens with a cooled full frame sensor should beat the Aero-Ektar with 4x5" film anyway (so no more lusting :-).

Chen

mikeinlehigh

I'll be looking forward to your next project using a regular camera lens and the 294. I use the ASI294MC Pro for all my regular astrophotography.